Normally, an alarm signal is transmitted directly from the protected premises to a commercial alarm receiving centre. When this signal is received, a manual verification process may commence to try and ascertain whether the signal is false or a true indication of an alarm condition at the premises. The outcome of any such procedure will determine whether the emergency services are informed of the alarm situation.
A significant percentage of alarm conditions relayed to the emergency services via commercial alarm receiving centres prove to be false alarms. In many cases these false alarms result from errors on the part of the alarm system user at the premises, e.g incomplete disarming of an intruder alarm as the premises are opened up at the start of the working day, or inaccuracies in the way in which an intruder alarm is armed at the end of the working day.
In order to more effectively filter these alarms conditions and thus reduce the number of false calls relayed to the emergency services, some organisations (such as banks, building societies, local education authorities), who operate high numbers of alarm sensors at diverse premises have set up their own "in-house" monitoring centres, which are used in place of commercial alarm receiving centres. These in-house alarm monitoring centres use their knowledge concerning the operation of their premises to filter signals more effectively and virtually eliminate false alarms due to user error.